A 2004 study of 43 food crops showed declines in six nutrients over the past 50 years, ranging from 7 percent less protein to 38 percent less riboflavin. “Declines are generally most easily explained by changes in cultivated varieties,” U.S. scientists concluded at the time. “There may be trade-offs between yield and nutrient content.” (NIH)

Scientists are now having second thoughts, and their revised conclusions are frightening. People may disagree about the reality or causes of global climate change, but all sides agree that the amount of carbon dioxide in our atmosphere is increasing.

And studies increasingly indicate that increased CO2 levels are having a dramatic effect on the quality of the plants we eat.

What’s that, you say? Shouldn’t more CO2help plant growth, since plants use carbon dioxide like animals use oxygen? Yes, CO2 enrichment can increase crop yield. But crop quality is another matter.

U.S. scientists studied soybean plants grown under various concentrations of carbon dioxide. They used an Agilent gas chromatograph to measure soluble carbohydrates and organic acids.